At this point I would say nobody in our first team is safe. If Pogba/De Gea/etc all want out, then they need to go.
We need a proper director of football structure in place and then targets need to be aggressively pursued - Solskjaer will likely want to play some sort of 4231 wide/counter attacking system.
As it stands we have no usable wingers, no real number 10, and we need another striker. There are plenty of promising young players out there who can come in: Lozano, Bailey, Neres, Havertz, Aouar to name a few.
That doesn't even touch on the defence which pretty much needs replacing entirely. I'd keep Dalot, Lindelof and probably Shaw (though he seems weird), and get in a couple of decent centre backs and another full back: Koulibaly, Militao, De Ligt (I wish), Hakimi, Ferland Mendy.
If De Gea causes problems, just use Romero for now, he's fine. I don't think Lukaku will work out long term either. Sanchez needs removing no matter the cost, he's been a disaster.
Of course none of this will likely come about - I have no idea what Woodward is going to do. Will be a very interesting transfer window, but if it goes like previous ones, it's going to be a pain too.
